Hypersalivation or excessive secretion of saliva is a symptom which can be very distressing for a person, and more so in a patient suffering from Parkinson’s disease, who already has to cope with so many other problems caused by the disease. Hypersalivation, leading to drooling, can be a manifestation of the condition or it can be due to drug therapy in Parkinson’s disease. There are various other causes for excessive salivation which may be superimposed in a person already suffering from Parkinson’s disease.
Causes of Hypersalivation
In a person suffering from Parkinson’s disease, the primary symptoms are tremor, rigidity, difficulty in initiation of movement and problems with posture, but there are several other secondary symptoms, one of which is hypersalivation or excessive secretion of saliva, often leading to drooling. Clozapine is an atypical antipsychotic drug used in the treatment of psychosis in Parkinson’s disease and in about one third of cases it causes hypersalivation and drooling as a side effect. The hypersalivation is more at night and may cause choking.
Other Causes of Hypersalivation in Parkinson’s
- Other medicines such as pilocarpine and nitrazepam.
- Metal poisoning with iron, lead, arsenic and mercury.
- Organophosphorus (acetyl cholinesterase) poisoning.
- Gastro esophageal reflux disease.
- CVA – stroke.
- Neuromuscular disease.
Complications of Hypersalivation
Apart from the social embarrassment causing decrease in the quality of life, hypersalivation leads to various other complications such as :
- Perioral irritation
- Ulceration around the mouth
- Fungal and bacterial infection around the mouth
- Choking due to excessive saliva
Treatment of Hypersalivation in Parkinson’s Disease
Obviously, the cause of hypersalivation has to be determined first – whether it is due to Parkinson’s disease itself, or Parkinson’s disease medicines, or other causes, and treatment is undertaken accordingly.
- Anticholinergics have been used in the treatment of hypersalivation or sialorrhea with variable results but the main difficulty is with administration of the drug and with its systemic side effects.
- Scopolamine dermal patch has been used for treating excessive salivation but tolerance develops quickly and side effects are common.
- Studies are going on regarding treatment of nocturnal clozapine induced hypersalivation by the administration of ipratropium bromide at bed time. It works by acting on the anticholinergic receptors with minimum systemic absorption and hence minimum systemic side effects. The efficacy of ipratropium bromide is being measured by the Toronto Nocturnal Hypersalivation Scale (TNHS).
- Intraglandular botulinum toxin injection into the parotid gland has been used in Parkinson’s disease to control excessive salivation but the response is temporary and may have to be repeated after 2 to3 months. The side effects of this treatment are xerostomia, pain at site of injection and temporary facial nerve paralysis.
- Various surgical treatments have been tried and submandibular gland excision with bilateral parotid duct ligation has been very effective for treating sialorrhea.
- Radiation is helpful in decreasing the secretion of saliva, especially in the elderly patient and those in whom surgery is not feasible, but the dose required may produce xerostomia.